Certificate Based authentication - FTP

I tried passing just the certificate information from the client without user name, ending up in an authentication error.
Is it possible to create an FTP session using only certificate based authentication without a user name?

I've never seen such setup before. Can you login using any other FTP client? If you can, post both its and WinSCP log file.

Found a similar approach to authenticate using only certificate not the user name and pwd. Find the link below.
https://stackoverflow.com/questions/29109291/is-there-a-way-to-use-ftpwebrequest-to-authenticate-to-ftp-using-client-certific

Also WinSCP client allows to authenticate using only certificate, it doesn't mandate user name. Where as from the programming side it is expecting user name.

Note that I have answered that Stack Overflow question. My code there uses username. So I do not see the relevance of the link.

Please post WinSCP GUI session log file that successfully authenticates without a username.

I am passing the user name now and providing the certificate (along with certificate passphrase).
I am getting a access denied error to the FTP site. Please suggest on this. Attaching the log file.

Once again, please post any log of any client that proves that authentication without username is possible.

Hi Martin, There was a confusion previously that winscp client was authenticating without user name but it prompted for user name later. So without user name authentication is not happening. I have configured FTP site for server based authentication and passing the certificate information from client, however there is a accessed denied error. Attached the log for same. Please suggest on this.

PS: Basic authentication is working fine with user name and pwd.

Ok, so can you login with the certificate using any other FTP client?